User interface for a portion of a display screen



The FIGURE is a front view of a user interface for a portion of a display screen showing the new design.

The broken line showings within the user interface and the unshaded areas within them form no part of the claimed design. The broken line showing of the portion of the display screen is for environmental purposes and forms no part of the claimed design. 

The ornamental design for a user interface for a portion of a display screen, as shown and described. 